A 2-month-old infant exclusively fed cow's milk-based formula develops a full-body rash. What is the most appropriate next step?

A 2-month-old infant exclusively fed cow's milk-based formula develops a full-body rash. What is the most appropriate next step?

• A. Switch to a soy protein based formula
• B. Switch to a high MCT oil formula
• C. Switch to a protein hydrolysate based formula
• D. Switch to a lactose free cow's milk based formula

Answer: (C)

The key idea is managing a suspected cow milk protein allergy in a young infant by reducing exposure to intact cow milk proteins. A full-body rash in a 2-month-old who is exclusively formula-fed strongly suggests CMPA, which occurs when the immune system reacts to cow milk proteins. The most effective next step is to switch to a formula in which the proteins are extensively broken down into small peptides, so they are far less likely to provoke an allergic response. This hydrolyzed protein formula is preferred over others because it addresses the underlying allergen exposure rather than just altering fat or lactose content. Switching to a soy-based formula is less ideal here because many infants with CMPA either also react to soy or are not recommended to rely on soy in early infancy. A high MCT oil formula targets fat absorption issues, not allergen exposure. A lactose-free cow’s milk formula removes lactose but still contains intact cow milk proteins, so it wouldn’t address the allergy. If symptoms persist despite a hydrolyzed formula, an amino acid–based formula may be considered.

The key idea is managing a suspected cow milk protein allergy in a young infant by reducing exposure to intact cow milk proteins. A full-body rash in a 2-month-old who is exclusively formula-fed strongly suggests CMPA, which occurs when the immune system reacts to cow milk proteins. The most effective next step is to switch to a formula in which the proteins are extensively broken down into small peptides, so they are far less likely to provoke an allergic response. This hydrolyzed protein formula is preferred over others because it addresses the underlying allergen exposure rather than just altering fat or lactose content.

Switching to a soy-based formula is less ideal here because many infants with CMPA either also react to soy or are not recommended to rely on soy in early infancy. A high MCT oil formula targets fat absorption issues, not allergen exposure. A lactose-free cow’s milk formula removes lactose but still contains intact cow milk proteins, so it wouldn’t address the allergy. If symptoms persist despite a hydrolyzed formula, an amino acid–based formula may be considered.